1. Field of the Invention
The present invention generally relates to wave energy conversion and, more particularly, is concerned with an apparatus for generating rotary motion from rise and fall motion of waves.
2. Description of the Prior Art
One of the more promising renewable sources of energy is ocean waves. Many devices have been proposed in prior art patents and literature for converting the energy of waves into a mechanical motion for performing work, such as generating electricity. In an article appearing in the September 1979 issue of IEEE Spectrum magazine entitled "Exploiting Wave Power", B. M. Count states that the first recorded patent was granted in 1799 to a Frenchman, M. Girard. Count goes on to state that all wave-power inventions to date have been conceptually simple--floats, flaps, sloping ramps or other "wave traps," or stationary air-pressure chambers and similar devices. He cites the emergence of two major categories of devices: dynamically active devices and passive devices. In the active device, the structural elements move in response to the wave, with power being extracted through the relative motion of the elements. A passive arrangement captures the wave energy with a relatively large, immovable structure. Being both bulky and relatively inefficient, passive devices are the least promising among suggested wave-power conversion schemes.
In a paper given in 1988 in Honolulu, Hawaii, entitled "Wave Energy: A Survey of Twelve Near-Term Technologies", investigators George Hagerman and Ted Heller grouped the major technologies for wave power conversion into five categories: heaving devices, heaving and pitching devices, pitching devices, oscillating water columns, and surge devices. Heaving devices use only the vertical motion of floats on waves to stroke various types of pumps. Combined heaving and pitching devices absorb energy from two or more motions of the waves, such as heave, pitch and roll. Pitching devices can be either floating or fixed. An oscillating water column device employs wave-induced motion of an entrained column of seawater as the driving force. Surge devices make use of a wave's forward horizontal force.
Notwithstanding the many different kinds of devices and approaches proposed in the prior art for capturing and converting wave energy to a form of motion for performing useful work, many technical problems still remain in harnessing wave energy. An optimal device has not yet appeared on the horizon.